How to Choose the Right MEMORY for your computer
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In building your own DIY PC Computer, one of the undeniable necessary ingredi
ents is MEMORY.
Be it a desktop, laptop, or handheld devices, knowingly or unknowingly, we come into usage of memory, be it volatile memory such as DRAM, SRAM or non-volatile memory such as ROM, flash memory.
Some common examples of non-volatile memory includes: CD-ROM, DVD-ROM, SD cards, and your typical thumbdrive. As for volatile memory, your computer memory will be a good example.
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Insights into the Computer Memory - What is DRAM ?
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The memory utilized in computers is commonly known as DRAM (Dynamic Random Access Memory)
The definition of DRAM according to Wikipedia, the free encyclopedia is as follows:
"Dynamic random access memory (DRAM) is a type of random access memory that stores each bit of data in a separate capacitor within an integrated circuit. Since real capacitors leak charge, the information eventually fades unless the capacitor charge is refreshed periodically. Because of this refresh requirement, it is a dynamic memory as opposed to SRAM and other static memory."
To make it simple, the DRAM is used by the computer to hold temporary instructions and data, hence facilitate fast access to stored instructions and data. It means that programs are loaded faster, running faster, with increase in efficiency and user experience.
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TECHNOLOGY TIMELINE
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Memory Technology has gone a long way as like computers, so it is cool to know the past history of DRAM.
YEAR INTRODUCED TECHNOLOGY SPEED LIMIT
1987 FPM 50ns
1995 EDO 50ns
1997 PC66 SDRAM 66MHz
1998 PC100 SDRAM 100MHz
1999 RDRAM 800MHz
1999/2000 PC133 SRAM 133MHz (VCM option)
2000 DDR SDRAM 266MHz
2001 DDR SDRAM 333MHz
2002 DDR SDRAM 434MHz
2003 DDR SDRAM 500MHz
2004 DDR2 SDRAM 533MHz
2005 DDR2 SDRAM 800MHz
2006 DDR2 SDRAM 667 - 800MHz
2007 DDR3 SDRAM 1066 - 1333MHz
2008 DDR3 SDRAM 1333 - 1600MHz
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How Much Memory Do I Need ?
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Based on different user requirements, different amount of workload is required of the computer, hence to enhance the efficiency, different memory configurations are also recommended as per below guidelines.
Extract from Kingston Technology website, the below is a summary of the baseline and recommended memory levels for different Operating Systems:
-->WINDOWS® VISTA
Requirements Entry Mainstream Performance High-end
Desktop 1GB – 3GB 2GB – 4GB 2GB – 8GB* 4GB to System max**
Notebook 1GB – 3GB 2GB – 4GB 2GB – 8GB* 4GB to System ma
-->WINDOWS® XP PROFESSIONAL and HOME
Baseline: 128MB - 256MB
Optimal: 512MB - 1GB
-->WINDOWS® 2000 PROFESSIONAL
Baseline: 128MB - 256MB
Optimal: 512MB - 1GB
-->WINDOWS® 98
Baseline: 64MB - 128MB
Optimal: 128MB - 256MB
-->LINUX
Baseline: 512MB - 1GB
Optimal: 1GB - 2GB
-->MACINTOSH™ OS X
Baseline: 512MB - 1GB
Optimal: 1GB - 2GB
-->WINDOWS® 2003 SERVER
Baseline: 2GB
Optimal: 4GB - 64GB
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UNDERSTANDING DRAM SPECIFICATIONS
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By and large, the most common DRAM memory seen for computers nowadays are commonly known as DIMMs(Dual In-line Memory Modules). They install vertically into expansion sockets, and come in various form factors and are specific to different DRAM technologies.
DIMMs transfer 64 bits of data at a time and are typically used in computer configurations that support a 64-bit or wider memory bus. However, the distinct difference between desktop and notebook DRAM is in the number of pins of the DIMM chip. A desktop computer nowadays uses a 240-pin DIMM while a notebook uses a smaller 200-pin SODIMM (Small Outline DIMM).
When we buy memory either online or at a local retailer, we are always presented with info in the following manner:
Eg:
4GB 4096MB-1600MHz DDR3 PC12800 240p DIMM
1GB 1024MB-667MHz DDR2-667 PC2-5300, 200p SODIMM
What exactly does all these numbers mean?
1) XX GB : Refers to the amount of actual memory. 1 GB = 1024 MB, and the more memory available, the more data that can be stored and the faster the performance.
2) DDR2/3 : Indicates the generation of DDR SDRAM (DOUBLE DATA RATE SYNCHRONOUS DRAM), with each improved generation, we are seeing higher memory bus clock rate, which improves the data rate.
2) DDR2-xxx: Denotes data transfer rate, and describes raw DDR chips
3) PC2-xxxx: Denotes theoretical bandwidth. Bandwidth is calculated by taking transfers per second and multiplying by eight. This is because DDR2 memory modules transfer data on a bus that is 64 data bits wide, and since a byte comprises 8 bits, this equates to 8 bytes of data per transfer. Eg: DDR2-667 --> 667 * 8 = 5300
| Standard name | Memory clock | Cycle time | I/O Bus clock | Data transfers per second | Module name | Peak transfer rate |
| DDR2-400 | 100 MHz | 10 ns | 200 MHz | 400 Million | PC2-3200 | 3200 MB/s |
| DDR2-533 | 133 MHz | 7.5 ns | 266 MHz | 533 Million | PC2-4200 PC2-43001 | 4266 MB/s |
| DDR2-667 | 166 MHz | 6 ns | 333 MHz | 667 Million | PC2-5300 PC2-54001 | 5333 MB/s |
| DDR2-800 | 200 MHz | 5 ns | 400 MHz | 800 Million | PC2-6400 | 6400 MB/s |
| DDR2-1066 | 266 MHz | 3.75 ns | 533 MHz | 1066 Million | PC2-8500 PC2-86001 | 8533 MB/s |
| Standard name | Memory clock | Cycle time | I/O Bus clock | Data transfers per second | Module name | Peak transfer rate |
| DDR3-800 | 100 MHz | 10 ns | 400 MHz | 800 Million | PC3-6400 | 6400 MB/s |
| DDR3-1066 | 133 MHz | 7.5 ns | 533 MHz | 1066 Million | PC3-8500 | 8533 MB/s |
| DDR3-1333 | 166 MHz | 6 ns | 667 MHz | 1333 Million | PC3-10600 | 10667 MB/s |
| DDR3-1600 | 200 MHz | 5 ns | 800 MHz | 1600 Million | PC3-12800 | 12800 MB/s |
Note: Although higher memory is always better, you also need to check other factors such as the memory bus clock rate versus the CPU clock rate, if the CPU cannot transfer data as fast as your memory chip, it would practically be a waste of money to buy something that is overspec. For example, your CPU runs at 800MHz, but the memory is running at 1600MHz, so the overall data transfer rate is still at 800MHz maximum. Get the picture? It is okay to be underspec, but meaningless and costly to be overspec.
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Installing your Memory Chips
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In building your own DIY PC, after installing your CPU, and motherboard, the next item will be your memory chips. You should spend some time planning and researching on memory which is compatible with the new CPU and motherboard you have installed to bring out the best overall performance. To install the RAM modules, you need to unfasten the clips located on each side of the memory slot. Align the RAM module in the socket, such as to match the indent located on the memory chip and the memory slot, for the right facing direction. Push down on the memory module until both clips refasten and a click sound is heard. To change memory, simply press down the both clips at the same time, and the RAM will come out easily.
TIP: Start adding RAM at the slot labeled “Bank 0” or “DIMM 1”. If you don’t, the system will think there is no memory available and wont boot.
TIP:For newer systems supporting hyper treading technology, you are encouraged to use the dual channel memory functionality by placing 2 sticks of the same memory on alternate slots (i.e.: slot 1 & 3 or Slot 2 & 4, often differentiated by color as well. ) This has been proven to enhance the performance as well.
For a better illustration, I have embedded a video to show you how you can install the computer memory easily.
With that i end off with a High Note: Have Fun Building Your Own DIY PC Computer !!
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